In modern medical engineering, medical image data are produced digitally in a wide variety of ways. Very widespread use is made of the production of medical image data by diagnostic modalities, such as computer tomographs, digital X-ray equipment, magnetic resonance imaging equipment and digital ultrasound equipment. Furthermore, medical image data are also produced by scanning in conventional X-ray films. Image data may also be in the form of endoscopically produced video films. In many instances of application, such as in a hospital, the medical image data are transmitted via a data network. In this data network, the modalities are often tied directly as network nodes. The modalities transmit the medical image data produced there to workstations for viewing and editing the medical image data and archive stores, for example, which are each also network nodes. Such data networks usually comprise a picture archiving and communication system (PACS). Particularly the storage, loading and transmission of the image data within the data network will subsequently be combined under the term “management”.
In the course of the technical development of the imaging systems, the volume of data which are transmitted in medical data networks has increased significantly. Particularly large volumes of data arise in sectional image diagnostics for multirow computer tomography or functional nuclear spin tomography. The increased spatial and temporal resolution means that volumes of data going into a two-digit gigabyte range arise. The transmission of such large volumes of data in the data network and the storage thereof in a memory within this data network represent a technical challenge. In particular, it is a problem transmitting the image data to the network node, such as a findings workstation, in real time and storing these volumes of data locally at sufficient speed. The respective modality as the source of the image data therefore often encounters a backlog in the transmission of the image data in the data network.
Currently, this problem is overcome by transmitting some of the data with a time delay, for example, if there is sufficient transmission bandwidth available in the data network. However, this neither reduces the total volume of image data to be transmitted nor speeds up the transmission of the image data per se.
To allow image data to be made available to a particular network node, such as a findings workstation, and displayed there in real time, it is possible to transmit the image data in rule-based fashion prior to a request to load the image data to the respective computer node. This rule-based transmission of the image data is also called “prefetching”. Prefetching assumes that it is already known in advance at what computer node the respective image data are required. The transmission rules are stipulated on the basis of organizational structures and processes, for example.
If these are not known or if the respective individual request differs from an expected behavior then prefetching is not a possible solution. In addition, the total amount of the data volume is not reduced by this method. In fact, the volume of data to be transmitted may even increase by virtue of the respective data being transmitted more or less as a precaution and, in the end, possibly not actually being needed at the respective computer node.
Particularly when viewing image data on a workstation, the display of the respective medical images can be speeded up by initially transmitting only portions of the respective image data which suffice for the display of an image at relatively low resolution or image quality. While this first coarse image is already being shown, the rest of the image data are transmitted retrospectively, so that finally the respective image can be shown at full resolution or image quality. This type of loading of image data is also called “progressive loading”. This type of image transmission can be used in appropriate fashion only to show the images but not to archive the images in a memory. Furthermore, even when the image data are displayed, the total volume of the image data to be transmitted is reduced by little or even not at all, depending on the respective specific method.
Specifically for 3D volume data, it is a known option to store these data at a network node in the form of a central server with a high level of processing power and to transmit to the remaining network nodes only 2D views of the 3D volume data which have been calculated by the central server. To this end, the respective data node sending a request to load the respective 2D image data to the central server sends respective specific 2D projection parameters for calculating the 2D projection view to the central server. To transmit the complete 3D volume data from the modality to a respective archive store, it is not possible to use this method.